Board foot calculator
List your boards, or measure a log. You get the board feet, the total at your price, and for logs all three log rules side by side.
Inputs
Result
What a board foot is
A board foot is 144 cubic inches: a board 1 in thick, 12 in wide and 1 ft long, or any shape with the same volume.
A 2x4 that is 8 ft long is 2 x 4 x 8 / 12 = 5.33 board feet. Softwood framing lumber is counted on its nominal size, so the 2x4 counts as 2 by 4 even though it measures 1-1/2 by 3-1/2. Hardwood is sold rough, by the quarter: 4/4 is 1 in thick, 6/4 is 1-1/2 in, 8/4 is 2 in.
Log rules
A log rule estimates the lumber a sawmill will get out of a log, so it is always less than the log's solid volume. The three in common use give very different answers, especially for small logs:
D is the small-end diameter inside the bark in inches and L the length in feet. Doyle underscales small logs badly; International 1/4 in is the closest to what a modern mill actually saws. The Scribner figure here is the common formula, which reads a little under the Scribner Decimal C table.
Questions
How do you calculate board feet?
Thickness in inches times width in inches times length in feet, divided by 12. A 1x6 that is 10 ft long is 1 x 6 x 10 / 12 = 5 board feet.
How many board feet is a 2x4x8?
5.33 board feet, using the nominal 2 by 4 size as lumber yards do.
How many board feet in a log?
It depends on the log rule. A 16 in log 16 ft long scales 144 board feet by Doyle, about 166 by the Scribner formula, and 200 by International 1/4 in.
Is a board foot the same as a linear foot?
No. A linear foot is just length. A board foot is volume: a 1 x 12 board 1 ft long. A 2x6 has 1 board foot in every linear foot.
Do I use the actual or nominal size?
Nominal for softwood dimension lumber, which is how it is priced. Rough hardwood is measured on its rough thickness in quarters, and surfaced hardwood is usually still sold on the rough board feet it came from.
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